1. Field of the Invention
This invention relates to a method and apparatus for abating emissions to the atmosphere from a leaking pressure relief valve secured to a pressurized container, such as a railroad tank car.
2. Description of the Prior Art
Inflammable gases like butane and propane and corrosive gases as anhydrous ammonia, chloride, and chlorine are stored for various reasons in movable or stationary containers and tanks. They are ordinarily held under pressure within the containers to more conveniently store them in a volume smaller than they would occupy without pressure. The exact amount of pressure in the tanks, however, must be maintained even though the surrounding temperatures within and around the tank vary. For example, the temperatures may vary as with a railroad tank car between 140.degree.F and as low as -50.degree.F, as it moves through the United States. Industry ordinarily achieves pressure control within the tanks by using safety relief valves.
The valves commonly used are ordinarily efficient, safe and reliable; nevertheless, on occasion they do develop leaks. This problem becomes especially significant when a container having a leaky valve is near populated areas like railroad sidings near factory and residential areas, for the leak may become the source of an explosion or air pollution. In some cases both of these events may occur together.
A typical safety valve is reciprocal within a cylinder or body. The reciprocal motion of the valve head and stem is responsive to pressure changes in the tank. In the normal position the upper expanded or flanged head is held in position by an elastic or resilient means, such as a helical spring. When a pressure increase has occurred, however, this upper end or head will move away from its seat so that the tank's contents can escape.
On occasion, however, the valve head may develop a leak because of:
IMPROPER VALVE HEAD RESEATING
SPRING FAILURE
STRUCTURAL DETERIORATION OF THE VALVE SEAT
OBSTRUCTIONS LIKE CORROSION OR DIRT ON THE VALVE SEAT OR STEM THAT PREVENTS PROPER VALVE FUNCTIONING OF THE VALVE ASSEMBLY. Obviously, these situations are undesirable since a leak may lead to a damaging explosion or environmental pollution.
The present invention will set forth a method and apparatus for gagging a valve (stopping a valve from leaking). In applying the invention, an easier, quicker way of stopping a valve leak than the currently used method of replacing or repairing a leaky valve on the spot results.